Pigment green and process for producing the same



Patented Nov. 23, 1948 PRODUCING THE AM William G. Huey, Nassau, andWalter G. Drautz, Glenmont N. Y., assignors to General Aniline & FilmCorporation, NewJY'ork; N. Y-;-, acme poration of, Delaware NoDrawing.Application necember, 2s,j1945; SerialzNo. 6372784 This-inventionrelates to the-.pmductionmf improved pigment green, 1; e., ir,oncomnlexesoi nitroso-fi-naphthol and. the products, thereof, having.improved texture characteristics and excellent working propertiesanditinctorial strength.

Theproductionofpigment comprising the iron complex of nitrosoedrnaphtholis well. known in the art, a particularly usefulmethod being disclosedin United States Patent No. 1,529,89lflf producing a pigment color oithis character which has a brilliant green hue and is known commerciallyas Pigment Green. In accordance with-this preferred methodof producingthe iron complex of-nitroso-p-naphthol, the nitroso-. fi-naphthol,preferably inthe form of itsbisulfite compound, is reacted-with ironsalts, particularly ferric chloride. This treatment may be conductedinthe presence or absence of substrates at ordinary or elevatedtemperatures. The resultant product exhibits goodfastness towards lightand alkalies but is relativelyhard'in textureand ver-y diflicult-todisperse. This hardness characteristic is especially pronounced ininstances where the pigment paste is permitted to dry outduringprocessing, such dry product becoming almost impossible to soften anddisperse. Accordingly, the use of pigment green has been largelyrestricted to thoseapplications in which it is possible to employaqueous pigment paste, although other methods have been suggested forimproving the texture properties of pigment green, for example, theincorporation of insoluble saltsof dispersing agents as disclosed inUnited StatesPatent No. 2,092,- 750 or treatment of .the material withcolorless organic amines, as disclosedin United States Patent No.2,259,641. The dried pigment cakes which have heretofore been I obtainedhave. a hard, shiny surfaceandiare sufficiently hard-that they finallyhave;to;be ground. I

We have discovered that if a small definite amount of water-immiscibleliquid is introduced; in the manner-hereinafter described, intoasolution of nitroso-fimaphthol during the course of production ofpigment green, a dried pigment cake is produced which falls apart at themerest touch and which also has markedly increased tinctorial strength.

The general method of preparing pigment green in accordance with thepresent invention involves the introduction of small amounts ofwater-immiscible liquids of the class of higher saturated andunsaturated aliphatic alcohols, fatty oils and viscous mineral oils intoa solution of nitroso-c-naphthol, preferably in the form of itsbisulfite or nitrite compound. The aqueous mixture is then treated Iwith an iron salt, preferably- -ferrous-sulf ate and l finallyprecipitated: with a solution ofsodium carbonate: to 'formthe insolublegreenpigment. While the water-immiscible liquid employed in the: presentinvention may advantageously be added=before the treatment with ironsalt, satisfactory resultsare obtainedby; adding" this waterimmiscible=liquid= at anytime before precipitation of-thepigment.

In order for an improved pigment to be obtained, the amount ofwater-immiscible liquid which is incorporated in the reaction mixturemust fall within the rangeof'from l'to 13% by weight, based on theweight of; nitroso-s-naphth0l', and'for maximum improvementinpropertiesv of the, pigment, an addition, in the range of from 2'to 6%by weight ofwvater-immiscible liq uid' is pre rred;

As examples of" suitable, water-immiscible liq uids. for, use inpracticing the present invention ma be, mentioned higher saturat dandurated aliphatic alcohols such as. cetyl" alcohol; oleylj, alcohol,octadecylj alcohol and mixtures of such. alcohols. such, as commercialmixturesv of Clfi. and, C18 unsaturated alcohols sold, under, thenameflof Ocenol, or other waterrimmiscible d-,- uidi alcohols.Variousjatty. oils, such as, linseed oil, cottonseed oil, ,oliveoil, andsimilar; fatty. oils arealso satisfactory. foruse in the,presentinvention,, Likewisamineral oils, particularly, viscous mineral.oil of the type ofwhite medicinal mineraloils may be employedimpracticing the. pres: ent invention, The particular water-immiscibleliquid is, employed, may; depend, to. some extentonthe art ,in which,ithetpigment which is to enmducedis empl r The, following;examplespillustratep the, invention: i r

Examplel 19 parts1 of nitrosorfi-naphtholv was solubilized in; aqueous.-solution with, about 20 .parts-of {Sodium bisulfite. The mixture wasthen filtered and treated with about 0.75 part of cottonseed oil. Themixture was thoroughly agitated and 9.5 parts of ferrous sulfatecrystals was then added. The pigment was precipitated by the addition ofdilute sodium carbonate solution in the usual way until the test isalkaline to Brilliant Yellow paper. The priciptated pigment was filteredand washed until neutral and then dried.

Example 2 The pigment was prepared as in Example 1 but .75 part of cetylalcohol was substituted for 0.75 part of Ocenol was substituted for thecot- I tonseed oil. The dried pigment powderobtained was substantiallyidentical with that obtained in Examples 1 and 2.

Example 4 19 parts of nitrosol-c-naphthol was solubiliz'ed in aqueoussolution with about 20 parts of sodium bisulfite. The mixture was thenfiltered and 9.5 parts of ferrous sulfate crystals were then addedandthereafter, while the mixture was thoroughly agitated, 0.75 part ofcottonseed oil was addedthen filtered and Washed until neutral, and thecake was then dried.

The dried pigment cake obtained in each of the foregoing examples had adull sheen and fell apart on mere touch in contrast to the dried cakeresulting from untreated pigment green or pigment green treated withother agents, which cakes may have a hard surface and are sufii cientlyhard that they have to be ground. This soft'chalky material is ofparticular value for coloring rubber and rubber compounds, eithernatural or synthetic, as it incorporates more uni formly with rubber,gives a greater surface area exposure, thus giving a marked increase intinctorial strength, together with. a desirable improvement in shade andshortening of the mill- V The use of these treated pigments ing process.is not limited, however, to coloring rubber, since they are broadlyapplicable for use in compositions in which a dried pigment powder isdesired. Thus, they may be employed in coloring such products as oil,coating compositions (paints and enamels) and the like. It willbeunderstood that the foregoing examples illustrate preferred embodimentsof the present invention and that various modifications may be madetherein by those skilled in the art. In particular, it should be notedthat other salts of nitroso-finaphthol may be used, for example, thenitrite; and other iron compounds may be used, for example, ferricchloride or ferrous oxalate. The amount of ferrous sulfate or other ironsalt employed may be varied somewhat from that given in the examples,but usually is not in excess of 1 mole of iron to 3 mols ofnitroso-fi-naphthol.

We claim: I

, 1. In a process for producing the iron complex of nitroso-B-naphtholwherein a salt of nitrosofi-naphthol is reacted'with an iron salt andthe 4 thus-obtained iron complex of nitroso-fl-naphthol is precipitated,the improvement which comprises incorporating in the reaction mixturebefore precipitation of the pigment, from 2-6% of awater immiscibleoleaginous liquid, and thereafter precipitating said iron complex,in-the absence of dispersing agents and insoluble sub 'strates, andrecovering and drying the same.

2. In a process for producing the iron complex of nitroso-B-naphtholwherein a salt of nitrosofi-naphthol is reacted with an iron salt andthe thus-obtained iron complex of nitroso-fl-naph- -tho1 isprecipitated, the improvement which comprises incorporating in thereaction mixture before precipitation of the pigment, from 2-6% of amixture of unsaturated alcohols largely con- Jtaining 16 to 18 carbonatoms, and thereafter precipitating said iron complex, in the absence ofdispersing agents andinsoluble substrates, and recovering and drying thesame.

"3'. In a process for producing the iron complex of nitroso-fl-naphtholwherein a salt of nitrosop-naphthol is reacted with an iron salt and.the thus-obtained iron complex of nitroso-fi-naphthol is precipitated,the improvement which comprises incorporating in the reaction mixturebefore precipitation of the pigment, from 2-6% of cottonseed oil, andthereafter precipitating said iron complex, in the absence of dispersingagents and insoluble substrates, and recovering and drying the same.

4. The soft green pigment consisting essentially of an intimate mixtureof the iron complex of nitroso-fi-naphthol and from 2-6% of awaterimmiscible oleaginous liquid and free of-dispersing agents andinsoluble substrates.

5. The soft green pigment consisting essentially of an intimate mixtureof the iron complex of nitroso-fl-naphthol and from 26% of unsaturatedalcohols composed essentially of alcohols containing 16 to 18 carbonatoms and free of dispersing agents and insoluble substrates.

6. The soft green pigment consisting essentially of an intimate mixtureof the iron complex of nitroso-fl-naphthol and from 26% of cottonseedoil and free of dispersing agents and insoluble substrates.

WILLIAM G. HUEY. WALTER G. DRAUTZ.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Nov, 8, 1935

